lib/agentx.c

   1 /* SNMP support
   2  * Copyright (C) 2012 Vincent Bernat <bernat@luffy.cx>
   3  *
   4  * This file is part of GNU Zebra.
   5  *
   6  * GNU Zebra is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the
   8  * Free Software Foundation; either version 2, or (at your option) any
   9  * later version.
  10  *
  11  * GNU Zebra is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with GNU Zebra; see the file COPYING.  If not, write to the Free
  18  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  19  * 02111-1307, USA.
  20  */
  21
  22 #include <zebra.h>
  23
  24 #ifdef SNMP_AGENTX
  25 #include <net-snmp/net-snmp-config.h>
  26 #include <net-snmp/net-snmp-includes.h>
  27 #include <net-snmp/agent/net-snmp-agent-includes.h>
  28 #include <net-snmp/agent/snmp_vars.h>
  29
  30 #include "command.h"
  31 #include "smux.h"
  32 #include "memory.h"
  33 #include "linklist.h"
  34 #include "version.h"
  35
  36 static int agentx_enabled = 0;
  37
  38 static struct thread_master *agentx_tm;
  39 static struct thread *timeout_thr = NULL;
  40 static struct list *events = NULL;
  41
  42 static void agentx_events_update(void);
  43
  44 static int
  45 agentx_timeout(struct thread *t)
  46 {
  47   timeout_thr = NULL;
  48
  49   snmp_timeout ();
  50   run_alarms ();
  51   netsnmp_check_outstanding_agent_requests ();
  52   agentx_events_update ();
  53   return 0;
  54 }
  55
  56 static int
  57 agentx_read(struct thread *t)
  58 {
  59   fd_set fds;
  60   struct listnode *ln = THREAD_ARG (t);
  61   list_delete_node (events, ln);
  62
  63   FD_ZERO (&fds);
  64   FD_SET (THREAD_FD (t), &fds);
  65   snmp_read (&fds);
  66
  67   netsnmp_check_outstanding_agent_requests ();
  68   agentx_events_update ();
  69   return 0;
  70 }
  71
  72 static void
  73 agentx_events_update(void)
  74 {
  75   int maxfd = 0;
  76   int block = 1;
  77   struct timeval timeout = { .tv_sec = 0, .tv_usec = 0 };
  78   fd_set fds;
  79   struct listnode *ln;
  80   struct thread *thr;
  81   int fd, thr_fd;
  82
  83   THREAD_OFF (timeout_thr);
  84
  85   FD_ZERO (&fds);
  86   snmp_select_info (&maxfd, &fds, &timeout, &block);
  87
  88   if (!block) {
  89     timeout_thr = NULL;
  90     thread_add_timer_tv(agentx_tm, agentx_timeout, NULL, &timeout,
  91                         &timeout_thr);
  92   }
  93
  94   ln = listhead (events);
  95   thr = ln ? listgetdata (ln) : NULL;
  96   thr_fd = thr ? THREAD_FD (thr) : -1;
  97
  98   /* "two-pointer" / two-list simultaneous iteration
  99    * ln/thr/thr_fd point to the next existing event listener to hit while
 100    * fd counts to catch up */
 101   for (fd = 0; fd < maxfd; fd++)
 102     {
 103       /* caught up */
 104       if (thr_fd == fd)
 105         {
 106           struct listnode *nextln = listnextnode (ln);
 107           if (!FD_ISSET (fd, &fds))
 108             {
 109               thread_cancel (thr);
 110               list_delete_node (events, ln);
 111             }
 112           ln = nextln;
 113           thr = ln ? listgetdata (ln) : NULL;
 114           thr_fd = thr ? THREAD_FD (thr) : -1;
 115         }
 116       /* need listener, but haven't hit one where it would be */
 117       else if (FD_ISSET (fd, &fds))
 118         {
 119           struct listnode *newln;
 120           thr = NULL;
 121           thread_add_read(agentx_tm, agentx_read, NULL, fd, &thr);
 122           newln = listnode_add_before (events, ln, thr);
 123           thr->arg = newln;
 124         }
 125     }
 126
 127   /* leftover event listeners at this point have fd > maxfd, delete them */
 128   while (ln)
 129     {
 130       struct listnode *nextln = listnextnode (ln);
 131       thread_cancel (listgetdata (ln));
 132       list_delete_node (events, ln);
 133       ln = nextln;
 134     }
 135 }
 136
 137 /* AgentX node. */
 138 static struct cmd_node agentx_node =
 139 {
 140   SMUX_NODE,
 141   "",                           /* AgentX has no interface. */
 142   1
 143 };
 144
 145 /* Logging NetSNMP messages */
 146 static int
 147 agentx_log_callback(int major, int minor,
 148                     void *serverarg, void *clientarg)
 149 {
 150   struct snmp_log_message *slm = (struct snmp_log_message *)serverarg;
 151   char *msg = XSTRDUP(MTYPE_TMP, slm->msg);
 152   if (msg) msg[strlen(msg)-1] = '\0';
 153   switch (slm->priority)
 154     {
 155     case LOG_EMERG:   zlog_err   ("snmp[emerg]: %s",   msg?msg:slm->msg); break;
 156     case LOG_ALERT:   zlog_err   ("snmp[alert]: %s",   msg?msg:slm->msg); break;
 157     case LOG_CRIT:    zlog_err   ("snmp[crit]: %s",    msg?msg:slm->msg); break;
 158     case LOG_ERR:     zlog_err   ("snmp[err]: %s",     msg?msg:slm->msg); break;
 159     case LOG_WARNING: zlog_warn  ("snmp[warning]: %s", msg?msg:slm->msg); break;
 160     case LOG_NOTICE:  zlog_notice("snmp[notice]: %s",  msg?msg:slm->msg); break;
 161     case LOG_INFO:    zlog_info  ("snmp[info]: %s",    msg?msg:slm->msg); break;
 162     case LOG_DEBUG:   zlog_debug ("snmp[debug]: %s",   msg?msg:slm->msg); break;
 163     }
 164   XFREE(MTYPE_TMP, msg);
 165   return SNMP_ERR_NOERROR;
 166 }
 167
 168 static int
 169 config_write_agentx (struct vty *vty)
 170 {
 171   if (agentx_enabled)
 172       vty_out (vty, "agentx%s", VTY_NEWLINE);
 173   return 1;
 174 }
 175
 176 DEFUN (agentx_enable,
 177        agentx_enable_cmd,
 178        "agentx",
 179        "SNMP AgentX protocol settings\n"
 180        "SNMP AgentX settings\n")
 181 {
 182   if (!agentx_enabled)
 183     {
 184       init_snmp(FRR_SMUX_NAME);
 185       events = list_new();
 186       agentx_events_update ();
 187       agentx_enabled = 1;
 188       return CMD_SUCCESS;
 189     }
 190   vty_out (vty, "SNMP AgentX already enabled%s", VTY_NEWLINE);
 191   return CMD_SUCCESS;
 192 }
 193
 194 DEFUN (no_agentx,
 195        no_agentx_cmd,
 196        "no agentx",
 197        NO_STR
 198        "SNMP AgentX protocol settings\n"
 199        "SNMP AgentX settings\n")
 200 {
 201   if (!agentx_enabled) return CMD_SUCCESS;
 202   vty_out (vty, "SNMP AgentX support cannot be disabled once enabled%s", VTY_NEWLINE);
 203   return CMD_WARNING;
 204 }
 205
 206 void
 207 smux_init (struct thread_master *tm)
 208 {
 209   agentx_tm = tm;
 210
 211   netsnmp_enable_subagent ();
 212   snmp_disable_log ();
 213   snmp_enable_calllog ();
 214   snmp_register_callback (SNMP_CALLBACK_LIBRARY,
 215                           SNMP_CALLBACK_LOGGING,
 216                           agentx_log_callback,
 217                           NULL);
 218   init_agent (FRR_SMUX_NAME);
 219
 220   install_node (&agentx_node, config_write_agentx);
 221   install_element (CONFIG_NODE, &agentx_enable_cmd);
 222   install_element (CONFIG_NODE, &no_agentx_cmd);
 223 }
 224
 225 void
 226 smux_register_mib (const char *descr, struct variable *var,
 227                    size_t width, int num,
 228                    oid name[], size_t namelen)
 229 {
 230   register_mib (descr, var, width, num, name, namelen);
 231 }
 232
 233 int
 234 smux_trap (struct variable *vp, size_t vp_len,
 235            const oid *ename, size_t enamelen,
 236            const oid *name, size_t namelen,
 237            const oid *iname, size_t inamelen,
 238            const struct trap_object *trapobj, size_t trapobjlen,
 239            u_char sptrap)
 240 {
 241   oid objid_snmptrap[] = { 1, 3, 6, 1, 6, 3, 1, 1, 4, 1, 0 };
 242   size_t objid_snmptrap_len = sizeof objid_snmptrap / sizeof (oid);
 243   oid notification_oid[MAX_OID_LEN];
 244   size_t notification_oid_len;
 245   unsigned int i;
 246
 247   netsnmp_variable_list *notification_vars = NULL;
 248   if (!agentx_enabled) return 0;
 249
 250   /* snmpTrapOID */
 251   oid_copy (notification_oid, ename, enamelen);
 252   notification_oid[enamelen] = sptrap;
 253   notification_oid_len = enamelen + 1;
 254   snmp_varlist_add_variable (&notification_vars,
 255                              objid_snmptrap, objid_snmptrap_len,
 256                              ASN_OBJECT_ID,
 257                              (u_char *) notification_oid,
 258                              notification_oid_len * sizeof(oid));
 259
 260   /* Provided bindings */
 261   for (i = 0; i < trapobjlen; i++)
 262     {
 263       unsigned int j;
 264       oid oid[MAX_OID_LEN];
 265       size_t oid_len, onamelen;
 266       u_char *val;
 267       size_t val_len;
 268       WriteMethod *wm = NULL;
 269       struct variable cvp;
 270
 271       /* Make OID. */
 272       if (trapobj[i].namelen > 0)
 273         {
 274           /* Columnar object */
 275           onamelen = trapobj[i].namelen;
 276           oid_copy (oid, name, namelen);
 277           oid_copy (oid + namelen, trapobj[i].name, onamelen);
 278           oid_copy (oid + namelen + onamelen, iname, inamelen);
 279           oid_len = namelen + onamelen + inamelen;
 280         }
 281       else
 282         {
 283           /* Scalar object */
 284           onamelen = trapobj[i].namelen * (-1);
 285           oid_copy (oid, name, namelen);
 286           oid_copy (oid + namelen, trapobj[i].name, onamelen);
 287           oid[onamelen + namelen] = 0;
 288           oid_len = namelen + onamelen + 1;
 289         }
 290
 291       /* Locate the appropriate function and type in the MIB registry. */
 292       for (j = 0; j < vp_len; j++)
 293         {
 294           if (oid_compare (trapobj[i].name, onamelen, vp[j].name, vp[j].namelen) != 0)
 295             continue;
 296           /* We found the appropriate variable in the MIB registry. */
 297           oid_copy(cvp.name, name, namelen);
 298           oid_copy(cvp.name + namelen, vp[j].name, vp[j].namelen);
 299           cvp.namelen = namelen + vp[j].namelen;
 300           cvp.type = vp[j].type;
 301           cvp.magic = vp[j].magic;
 302           cvp.acl = vp[j].acl;
 303           cvp.findVar = vp[j].findVar;
 304           /* Grab the result. */
 305           val = cvp.findVar (&cvp, oid, &oid_len, 1, &val_len, &wm);
 306           if (!val) break;
 307           snmp_varlist_add_variable (&notification_vars,
 308                                      oid, oid_len,
 309                                      vp[j].type,
 310                                      val,
 311                                      val_len);
 312           break;
 313         }
 314     }
 315
 316
 317   send_v2trap (notification_vars);
 318   snmp_free_varbind (notification_vars);
 319   agentx_events_update ();
 320   return 1;
 321 }
 322
 323 #endif /* SNMP_AGENTX */